De-cat 4.0 chim

[Flyin Banana]

when de catting the chim(p) what do people do remove all cats pre and in the y piece or just pre cats or just y piece and how noisey will it get !!!


Rob

[steve j]

Hello Rob, I`ve been through the lot, precats out, main cat in, not much noisier, precats and main cat out, a fair bit louder, then the whole hog with sleeved silencer very loud indeed, especially as you`re sitting in a plastic resonance chamber . I`m now running with precats out, main cat in (for MOT purposes) and sleeved silencer, it`s bearable even on a run.

[Paulprior]

I have also just removed the precats with everything else standard, a bit louder but not huge, my wife hasn't noticed😀

[bobfather]

Decatting the headers is an awkward job, there isn't a direct route to the wad so you'll find yourself trying to work around a corner. You need to be careful not to put any stress on the 4 into 1 connection because the welding of the hidden inner pipe connection is susceptible to corrosion and subsequent weakening. Failure of that area is regularly reported hear and I was a sufferer.

I fitted ACT catless headers. They sound crisper than the originals but unfortunately ACT contract out the manufacture and now material quality has become very poor. Heat tint is patchy indicating inconsistencies in the material.

I also fitted a Clive F Y Piece, this on the other hand is made of high quality material and has a fantastic sound

[Flyin Banana]

not really looking for a noisy car want the engine to breath a little better and hopefully give the 4.0 a little more push !!

thanks for all the advise so far

[caduceus]

IMO precats and main cat out with standard silencer in is the best combo. Breathes better, noticeably, sounds better but not like a tug boat and you get more pops and bangs on overrun.

[Squirrelofwoe]

caduceus said:

IMO precats and main cat out with standard silencer in is the best combo. Breathes better, noticeably, sounds better but not like a tug boat and you get more pops and bangs on overrun.

I've gone the other way with my 4.0 - both pre & main cats still in place, but with a 'sleeved' silencer.

Absolutely love the sound! The closest thing I can liken it to is a WW2 aircraft.

Not a huge amount more outright volume than the standard system, but a lot more pops, bangs, and general drama.

[Martin W]

I've just been thinking about this scenario again recently myself and was going to start a thread on the subject...

I had my exhaust sleeved and pre-cats removed by David Batty probably around 8 or 9 years ago and I was pretty happy with the sound, but then a couple of years later I added a CF y-piece too which took it to a whole new level. Under full load the sound was phenominal (and obviously very loud) but around town and especially at traffic lights, it was frankly more Massey Ferguson. I sold the y-piece probably around 5 years ago and hadn't thought much more about it... The sound of my Chimaera doesn't sound quite as I want it to and I'm starting to think that perhaps I should have tried Clive's Y-piece without a sleeved exhaust; I'm now contemplating buying one again and reversing the sleeve.

To try to save me the aggro and potential waste of money, does anyone have recordings of their unsleeved decatted Chimaeras that they could share with the community?

[QBee]

Flyin Banana said:

when de catting the chim(p) what do people do remove all cats pre and in the y piece or just pre cats or just y piece and how noisey will it get !!!


Rob

Hi Rob
I have the 5 litre engine in mine.
Precats out
Y piece replaced with Clive Ford Y piece, so no cats at all.
Standard exhaust

It's louder, makes a nice noise, but still passes track day noise limits, though I do always have to take ACT clamp-on silencers with me to make sure, as the noise test can be trickier on a cold damp day. At Cadwell Park last month (hot day) it was 101 db. It has been 107db there on a cold damp day.

[keith-vznby]

Have just fitted ACT manifolds with reverse cones, no precats, already had Clive Y piece and half sleeved silencer the sound is nice without being overly loud I think fully sleeved would be to much

[SILICONEKID345HP]

In happy with pre cats out , clives Y piece and standard exhaust .

Im not sure if the diameter of the Y piece needs to be that wide , you do get a bit of a clatter nois. I would prefer the act setup but it means spending .

[SILICONEKID345HP]

SILICONEKID345HP said:

Im happy with pre cats out , clives Y piece and standard exhaust .

Im not sure if the diameter of the Y piece needs to be that wide , you do get a bit of a clatter nois. I would prefer the act setup but it means spending .

[andy43]

I've put a Clive f y piece on in the last couple of weeks. Std exhaust and cats was ok. Then I went to act de catted manifolds - not much difference at all. Now the y piece is on its transformed it - deep bassy throb sounds way better from the cabin, and it proper howls at high revs. And it looks Stonking under the bonnet.
Std cats and a straight through exhaust is very tug boat idle from the cars I've heard, but OK higher up the Rev range. Decat and sleeved is just plain mental, must be wearing on a long journey.
Complete Decat and std exhaust as I've got now is bestest imho.
Why this iPad inserts random Capitals I've no idea

[Belle427]

Pre cats out and a Clive y here too, sounds just about right in my opinion.

[ChimpOnGas]

Pre-cats removed - ACT "Y" piece (so no main cat) - standard exhaust

Perfect

[TV8]

Decat plus ACT Cherry bomb system is pretty damm good. Actually quieter on part throttle at speed than the standard system with decat and sounds amazing when trying a bit harder. It can also set off car alarms in multi-story car parks...